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Study suggests eco-driving techniques could reduce public transit fleet fuel consumption by up to 18.7%

31 March 2012

Transit fleets could reduce fuel consumption on average by as much as 18.7% by engaging in fuel-efficient, eco-driving best practices, according to a Public Transit Fuel Efficiency Study released by SmartDrive Systems, a provider of fleet management and driver safety systems and services.

Eco-driving best practices for public transit include smooth acceleration and deceleration; reducing excess idling; avoiding hard turning (anticipating turns and smoothly decelerating into the turn to take advantage of the bus’s forward momentum and smoothly accelerating out of it); and maintaining constant vehicle speed.

The study evaluated several hundred transit buses and drivers in multiple US locations and from various manufacturers, including Eldorado, Flxible, Gillig, New Flyer, Orion, Prevost, Nova Bus, and Thomas Built to assess the effect of driving performance on fuel consumption and determine the impact of training and in-vehicle instant feedback on improving fuel economy. Study data was compiled by SmartDrive sensors and recorders, then analyzed and training recommendations provided.

The study measured at several key indicators and driving maneuvers known to impact fuel use and economy:

  • Actual fuel use: as measured in miles per gallon from the Engine Control Unit (ECU)
  • Idling time: how much time was spent with the engine running while no movement was recorded for greater than three minutes
  • Acceleration: the incidence, frequency and severity of quick starts and sudden acceleration during travel as measured by accelerometer and ECU
  • Braking: hard braking defined by speed from the ECU, duration of deceleration and G-force effect measured by the accelerometer
  • Turning: hard turning/cornering measured by speed from the ECU and G-force from the accelerometer

During the control period, the SmartDrive system recorded the following inefficient driving maneuvers:

  • 17.8 hard accelerations performed on average per hour;
  • 9.5 hard braking events performed on average per hour; and
  • 3.9 hard turns performed on average per hour.

Real-time in-vehicle feedback on driving maneuvers and idling gave drivers the ability to adjust driving performance as it happened. Post-training performance was measured showing substantial reductions in the number and severity of hard accelerations, hard decelerations and hard turns.

With the volatility of fuel prices, reducing fuel consumption is increasingly important in controlling operating expenses for public transit fleets. Our study documented a significant opportunity to increase fuel efficiency by addressing the 84.8% of fuel waste that can be improved through softer driving. The study also shows that training and real-time in-cab feedback combine to dramatically lower the incidence of wasteful maneuvers.

Within one month, the top 25% of drivers improved their fuel economy from 3.87MPG to 4.59MPG, or 18.7%.

—SmartDrive President Jason Palmer

Conclusions and recommendations for public transit fleets resulting from the study include:

  1. The greatest opportunity in fuel efficiency comes from the way a vehicle is operated, particularly hard driving maneuvers. Identifying inefficient driving habits and reinforcing best practices leads directly to improved performance and reduced operating costs.

  2. Providing drivers with immediate feedback in the vehicle allows them to make quick corrections and learn over time how to most efficiently operate their vehicle. Substantial week-to-week improvements indicate that drivers are adopting and adhering to eco-driving techniques that improve fuel efficiency.

  3. For quick results, deliver additional training with constructive guidance to the drivers that show the highest number of inefficient driving events. The combination of real-time feedback and focused training drives significant and immediate impact on overall fleet fuel consumption. In this study, in less than a month, the top 25% of drivers with the greatest improvement in fuel economy reduced fuel use by an average of 18.7%, resulting in an annual average fuel savings of $3,392 per vehicle.

To further help drivers improve their fuel efficiency, SmartDrive has released a short Eco-Driving Training Video, designed specifically for public transit.

March 31, 2012 in Behavior, Fleets, Fuel Efficiency, Heavy-duty | Permalink | Comments (16) | TrackBack (0)

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3.87MPG to 4.59MPG (or 4 to 5 mpg in UK gallons) makes this still a very high figure, but its not surprising given the stop-start nature between stops and in urban traffic conditions.

If I do the maths right, you'd need at least 6-8 people to be using a bus to make it as fuel efficient as a single occupant driving an average car (not SUV obviously!!), and if a car has more occupants, multiply that number for a bus to be more efficient. So, say a car with 3 people will need a bus to have 18-24 people to be equally efficient on a miles per gallon per passenger basis as a car with three passengers.

I know that buses would be more efficient if more people used them, but this only depends on whether the bus in question is actually taking the route that people want to travel on and at the time they need it. And it also needs to be quick, not diverting round countless housing estates, as most do.

This then doesn't make buses as efficient as some people make them out to be. But is this a reason to suggest buses are a bad thing? No. They still provide useful mobility to people who don't have a car or who don't want the hassle of commuting, provided of course that the said bus provides a convenient alternative. So they have a purpose, much like cars which meet different journey types. They also make better use of roadspace especially in dense urban cities.

Hence having a diversity of ways of getting about is a good thing for choice, rather than adopting a restrictive attitude, like some people and politicians of a more greener persuation who adopt a autophobic attitude even to people who only have the car as an option.

They might also consider including smaller buses and vans in their fleets for routes and times that typically carry a small number of passengers.

Buses are a fantastic form of transport for cities: you can fit about 90 people on them in rush hour, and you don't have to park them.
and so on, ...

However, I often see them being driven very fast with hard acceleration as described in this article.

So why don't more transport companies try to train their drivers in eco-driving.

I have a few thoughts here:

a: The drivers are stressed out, and use the acceleration as a way of relieving their stress.

b: The drivers are so unionised that management won't say boo to them.

c: Management just couldn't be bothered.

So what could they do:

a: Train them, obviously.

b: Give them some kind of bonus for eco driving.

This could be 10% of the fuel saved or whatever.
The problem is that if they got wind of the system, they would drive very badly in the month before the system started when the targets were being set, and would generally game the system.
Also, how long would you run such a scheme, and how would you phase it out ?
What would happen if you got hybrid buses?

Another idea would be to use smaller buses on the same routes at the quiet times - I often see buses flying past my window at about 50mph with 3 or 4 people on them.

Again, extra complexity and hardware for some fuel savings.

Easier to just get the guys to slow down and anticipate stopping.

I agree with Mahonj with one exception...the ladies driving our city buses seemed to be naturally inclined towards safer eco-driving. Progressively replacing all arrogant male drivers with polite lady drivers could be the lowest cost way to achieve this goal.

Hard acceleration does NOT mean less efficient engine operation, for gas or diesel (short of WOT, where extra enrichment is often provided); so these algorithms and arguments are flawed.

Leisurely accelerating a 15 ton bus (and the irate drivers following) to 30mph only to ALMOST make the traffic light is very inefficient.

Reasonably hard acceleration, braking and cornering are not what is inefficient - they are simply the easiest indication or measure of inefficient driving.

The real goal is to drive with very little breaking.

So rather than trying to make hundreds of bus drivers drive like old ladies, how about providing traffic notifications regarding how to make (or slow since you will NOT make) the next light – for ALL vehicles/drivers to use.

We’ve covered this before – even those pedestrian cross walk timers are WAY better than nothing.


Reasonably hard acceleration is not a sin.

Those who arrogantly believe that simply imposing more restrictions on others is intrinsically good should be sent to Cuba.

Restrictions and laws make the difference between humans and other four legged species. The far west six shooters days are over.

You must be a politician.

Most of us think that each law is evidence of failure and is often a worse failure than the original.

First God created time;
then God created man
that man might, in the course of time, perfect himself;
then God decided that He'd better create eternity. ~Robert Brault.

A bus taking its own sweet time to slow down for anything except a traffic light, and taking its own sweet time to get up to speed again, is a bus that's taking considerably more time to get somewhere.  So is the traffic stuck behind it.

Hard turns are good for fuel economy. Not slowing down to a crawl for the turn means less acceleration is required afterward.

Buses should have some sort of hybrid system, such as hydraulic accumulators.  Capturing the braking energy and using it to return to speed quickly allows higher average speeds without wasting fuel.

OK TT, I accept your comment on acceleration.
Brisk acceleration should be encouraged - just don't exceed the speed limit too much and anticipate braking.

(Or whatever a proper eco-driving course would teach.)

From leaked info, the average lady city bus driver already gets 25% more mpg and up to 30% less accidents than our arrogant overly union active male counterpart and have higher respect for schedule times, passengers, pedestrians and other drivers.

Our average city bus drive cost a total of $123.500/year. Small buses are out except for special buses for disabled. Much longer 2 and 3 coupled units with one overly paid arrogant driver are moving in fast.

Arrogant, aggressive, males drivers should be transferred to subways, urban e-trains, long distance buses with isolated driver cab where they can do their bad manners with less damages.

What's with this preoccupation with aggression and sexism?

I think the question may be - how do we get the men to drive more like the women without going postal on us.

Why should one gender HAVE to drive like another? We are entering the age of energy abundance and saving a few gallons of diesel will become meaningless. Of course for the moment it's nice to save fuel - especially fossil fuel.

I've ridden buses in big cities for years and have yet to encounter an "arrogant, aggressive male driver." Job preservation dictates that.

Reel$$...come and visit us for a few days and ride our city buses and you will change your mind set.

Eco-driving is about anticipation of what is coming, not about driving slowly.

Particularly for buses that need to stick to a schedule, accelerating to avoid a red light can save a huge amount of fuel, if only the driver uses the time saved to coast to the next stop (when feasible and possible, of course). Furthermore, if you drive the same city route day in, day out, it is not too much to ask to 'know the lights' if they run on timers. I use that all the time to anticipate the correct speed approaching an intersection. I absolutely loathe to come to a full stop only to have a green light one second later. That is bad timing on my part and I beat myself up over it.

High cornering speed is also good for fuel economy - and average speed - but not always feasible with a bus where people are standing up.

I remember hearing that the open-pit tar sand operations like/prefer female drivers for the enormous dump trucks because they cause less wear on the equipment while being just (guessing) 2% slower.

Well said, Thomas.... good mileage comes from looking ahead and paying attention to traffic lights. Many drivers power toward red lights, then stop abruptly.... just as the light turns green and they restart again. Double waste, both fuel and gas.... and some safety loss also, reducing speed ahead greatly reduces the chances of hitting the stopped vehicles in front of you in poor conditions.

Most of the lights that I drive through have predictable patterns.... no need to race toward a light that you cannot possible make.

The most ridiculous waste that I can think of: My city put in synchronized traffic lights on two one way streets FIFTY years ago. The lights are synchronized at a speed slightly below the limit, as traffic is often heavy in this area.

The waste: MANY drivers accelerate briskly toward each light, brake hard, nearly stop, gun it again as it turns green FOR THE ENTIRE 30 BLOCK DISTANCE. After 50 years they have paid so little attention to their driving that they have not noticed yet!!

I suspect many hypermilers make better time than most drivers, while getting much better mileage. Those that pay attention generally win!!

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